Why is TPMT Testing Important?

  • Detection of individuals with low thiopurine methyltransferase (TPMT) activity who are at risk for excessive myelosuppression or severe hematopoietic toxicity when taking thiopurine drugs.
  • Detection of individuals with hyperactive TPMT activity who have therapeutic resistance to thiopurine drugs and may develop hepatotoxicity if treated with these drugs.

Video Overview

Available Tests and Advantages of Each

When to Order (click to enlarge)

1. Moriyama T, Nishii R, Perez-Andreu V, et al. NUDT15 polymorphisms alter thiopurine metabolism and hematopoietic toxicity. Nat Genet. 2016 Apr;48(4):367-73.
2. Roberts RL, Barclay ML. Update on thiopurine pharmacogenetics ininflammatory bowel disease. Pharmacogenomics 2015; 16: 891-903.
3. Goel RM, Blaker P, Mentzer, A, et al. Optimizing the use of thiopurines in inflammatory bowel disease. Ther. Adv. Chronic Dis. 2015;6(3):138-146.

Algorithm (click to view PDF)